A traditional refrigeration cycle apparatus that supplies a cooling target fluid cooled to an intended temperature directly measures the flow rate of the cooling target fluid using a flowmeter or other measuring instruments. Such a refrigeration cycle apparatus detects a flow-rate fault of the cooling target fluid or other faults caused by freezing or the like using the directly measured flow rate of the cooling target fluid. Thus such a refrigeration cycle apparatus needs to include the measuring instrument (flowmeter or the like) for directly measuring the flow rate of the cooling target fluid. This raises a problem that the refrigeration cycle apparatus is expensive.
To address this, refrigeration cycle apparatuses that aim to detect a flow rate or a flow-rate fault of a cooling target fluid without including a flowmeter have been proposed.
One example of the proposed traditional refrigeration cycle apparatuses aiming to detect the flow-rate fault of the cooling target fluid without including the flowmeter is “a cooling apparatus 100 that includes refrigeration cycle means including a compressor 1, a condenser 2, throttle means 4, and an evaporator 5, the cooling apparatus 100 including an air-sending device 3 for blowing air to the condenser 2, low-pressure refrigerant liquid temperature detecting means 10 for detecting a temperature of a low-pressure refrigerant liquid flowing in the evaporator 5, cooling target fluid inflow temperature detecting means 11 for detecting a cooling target fluid flowing in the evaporator 5, a computing unit 21 receiving a temperature of a detected value, a determining unit 23 determining ‘the presence or absence of freezing of the cooling target fluid’ or ‘the possibility of freezing,’ and a control unit 24 controlling the compressor 1, the air-sending device 3, the throttle means 4, and a pump 6 to prevent freezing of the cooling target fluid on the basis of a result of determination by the determining unit 23” (see, for example, Patent Literature 1).
One example traditional refrigeration cycle apparatus that aims to detect a flow rate of a cooling target fluid without including a flowmeter is one in which the flow rate of coolant water is estimated on the basis of measured data on a flow rate of cold water flowing in an evaporator, a temperature of the cold water at an entrance, a temperature of the cold water at an exit, an intermediate temperature of coolant flowing from an absorber to a condenser, and a temperature of the coolant flowing in the absorber at the entrance (see, for example, Patent Literature 2).
Another example traditional refrigeration cycle apparatus that aims to detect a flow rate of a cooling target fluid without including a flowmeter is one in which a refrigeration load is calculated from measured data on a flow rate of cold water flowing in an evaporator, a temperature of the cold water at an entrance, and a temperature of the cold water at an exit, the ratio between the amount Qa of heat received from the cold water and the amount Qe of heat transferred to the coolant (heat exchange coefficient K) is calculated on the basis of the temperature of the coolant and the refrigeration load, and the flow rate of the coolant is calculated on basis of the calculated heat exchange coefficient K (see, for example, Patent Literature 3).